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Comment by jhallenworld | Hacker News Reader

This video generator is not hard to write in Verilog (or better, System Verilog) either. Seriously, synchronous code like this is the easy part.

See where they show the block diagram in Vivado? That's the difficult part. You had to use the clock wizard to configure the PLL. You had to figure out how to convert the generated Verilog into one of those blocks. You had to choose the I/O standards, assign the pinout and set up timing constraints. You had to figure out how to get the block diagram saved into version control..

That block diagram is stored as, you guessed it, an XML file. But it can also be generated from or saved as a TCL script.. Also it has an associated Verilog wrapper... If it gets messed up, you will be editing the XML file..

If they really want to make Vivado easier to use, that block diagram would be gone.

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The block diagram is optional, everything can be done in Verilog. That said, I use IPI and find it very productive. Module reference flow lets you wrap Verilog modules and expose IO as interfaces so composing a top level in the block diagram and hooking everything up is easy.

It is optional but the alternative is also a pain to figure out and setup.

I completely agree, and I use IPI myself as I find it adds more than it costs, I was just pointing out its not mandatory as OP was not a fan

Well suppose you want your code to connect with IPI interfaces from Xilinx IP. You end up having to annotate it with magic attributes like this:

    (* X_INTERFACE_INFO = "xilinx.com:signal:clock:1.0 clk CLK" *)
    (* X_INTERFACE_PARAMETER = "ASSOCIATED_BUSIF disp1_tpg_axis:disp2_tpg_axis:ar_tpg_axis:artx0_axis:arrx0_axis:scaletx0_axis:tmrx0_axis:scaler, ASSOCIATED_RESET reset_l, FREQ_HZ 199980011" *)
    input clk;

    (* X_INTERFACE_INFO = "xilinx.com:signal:reset:1.0 reset_l RST" *)
    (* X_INTERFACE_PARAMETER = "POLARITY ACTIVE_LOW" *)
    input reset_l;

    (* X_INTERFACE_INFO = "xilinx.com:interface:rx_mipi_ppi_if:1.0 cam0_rx_dphy DL3_RXDATAHS" *)
    input [7:0] cam0_rx_dphy_dl3_rxdatahs;

It's horrible. Trust me, you will not like when things go wrong in larger block designs.

That's right, I already do annotate my signals that way. It doesn't bother me as I know doing this will ensure connections can be validated at the block diagram level. Clock and reset domains will be correct, interfaces that are incompatible cannot comnect.

It's clear you have been burned, but I'm genuinely curious as to how. I've always found it to be smooth, and you can write a tcl representation of your bd for safe keeping, and what is generated is very readable (write_bd_tcl)

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